@nanofrog: Thanks for your detailed response. I really appreciate that.
No problem.
Details are really needed when dealing with RAID. Otherwise, you're libel to end up with a system that won't suit your needs, or possibly not function at all.
So you are saying that internal hardware raid in the 09 models is completely impossible right now unless I use the Apple card or "hack" the optical bays?
Not quite.
You can, but it would mean removing the optical drive(s) and placing them in external 5.25" enclosures, and using the bays for the RAID drives. Depending on what you can buy or make, you can squeeze in 4x 3.5" HDD's, or even 8x 2.5" drives. Perhaps a little shoe-horned, but it's possible. Somehow I think many might not want to place the optical drives externally though, as it's not that attractive.
Since I am still thinking of only doing raid 10, I might as well just skip hardware raid and keep using software raid. I would need to use an external eSATA enclosure to get my six drives. I am wondering if eSATA can give me the same performance as internal SATA?
eSATA runs at the same speed as SATA (300MB/s).
Just the cables are slightly different (shielding is added).
Why would you need to use eSATA? (Necessity)?
eSATA can simplify things, and has a lower cost associated with it, but it isn't the fastest way to go. Most of the time, multiple drive enclosures use a Port Multiplier (PM) to switch all drives on a single SATA port, hence the throughput limits. It may, or may not matter, depending on your throughput requirements. For small arrays, it won't really make a difference. Ideally, you want 1 port attached to 1 drive. An eSATA card and 2 simple enclosures w/ eSATA ports wouldn't be too terrible, but it might hit the cost of a better RAID card, depending on what features you want. You'd have to run the numbers.
Just thinking... if an external enclosure with two disks only has one eSATA port, wouldn't that limit the performance?
In this case, PM enclosure, there would be a penalty in throughput, but for two drives, it may not be bad. What I'm not sure of, is if it would make a difference in operation (set-up even possible) under OS X.
To explain, you'd have individual drives attached internally, but I don't know how it would "like" these being added with another two via a PM device on a single port. The drivers may not be capable of it in an OS X environment.
My current idea is to populate the internal 4 bays with 4 * 1 TB and use eSATA with 2 * 1 TB. This way I could have two raid 0 stripe sets (2 * 3 disks) and mirror them with raid 1. However, if the eSATA does not perform like internal SATA, that will be a no go.
See above.
It's the OS X aspect I'm a little uncertain of, as I've not used PM enclosures in a good while, and not split in the manner you want. Never on a Mac, as it happens.
I stick to RAID cards, and software based ZFS/RAID-Z/RAID-Z2 via iSCSI/AoE rigs, when needed, for external backup (DIY). Otherwise, I just make a duplicate array (not a mirror).
Are there any RAID cards in the 100-250$ range that offer RAID 0, capability to boot 0SX, and use bootcamp for Windows XP and 7?
Maybe, but it would take some searching, for sure to hit that price point. All you'd really be able to find is "Fake RAID", which is nothing more than a drive controller chip, firmware (for boot), and drivers. NO cache, IOP, etc.
You might want to check out HighPoint, as they're going to be your best bet. SATA/eSATA cards from other vendors as well.
